The chemical industry continually develops new olefin polymerization catalysts, catalyst activation processes, and methods of making and using catalysts that will provide enhanced catalytic activities and produce polymeric materials tailored to specific end uses.
One type of catalyst system comprises so-called single site organometal compounds, particularly metallocene compounds and transition metal compounds. Metallocenes have been well explored, but less is known about the polymerization behavior of transition metal compounds. It is believed that transition metal compounds, those compounds that do not have a cyclopentadienyl, indenyl, fluorenyl, substituted cyclopentadienyl, substituted indenyl, or substituted fluorenyl group bound to the metal atom and are thus not metallocenes, may offer the potential to produce polymers with improved properties, as well as lower cost. Also of interest is the development of transition metal compound-based catalytic systems that can be activated with a variety of activating agents without requiring the use of relatively expensive aluminoxane or borate co-catalysts, yet still provide relatively high polymerization activities.
Therefore, new catalyst compositions and methods of making the catalyst compositions are needed to afford high polymerization activities, and to allow polymer properties to be designed within the specification ranges for the desired end-use application.